Why does everything look backward in a mirror?

Everything looks backward in a mirror due to the way mirrors reflect light. When you look into a mirror, it reverses the image along the axis perpendicular to the surface, which is often interpreted as a left-right reversal. This occurs because the mirror reflects the light rays in their original direction instead of reversing them, leading to the perception that right and left are swapped. However, the top and bottom of the image remain unchanged, which is why the effect can seem counterintuitive.